Laimiux

sealed class CommentFormUserEvent {
  data class TextChangedEvent(..): CommentFormUserEvent()
  data class SubmitCommentRequestEvent(..): CommentFormUserEvent()
}

sealed class LoginFormUserEvent {
  // We cannot use TextChangedEvent from CommentFormUserEvent
  data class TextChangedEvent(..): LoginFormUserEvent() 
  data class LoginRequestEvent(..): LoginFormUserEvent()
}

Laimiux

fun reduce(event: TextChangedEvent): (CommentFormData) -> CommentFormData {
  // implementation
  return { state -> 
    // Let's check comment validity
    val isValid = event.enteredText.length > 5
    // Update the current state with the changes
    return state.copy(comment = event.enteredText, isCommentValid = isValid)
  }
}

Laimiux

fun reduce(event: TextChangedEvent): Reducer<CommentFormData> {
  // implementation
}

fun reduce(event: Lce<Comment>): Reducer<CommentFormData> {
  // implementation  
}

 fun formState(

Laimiux

data class CommentFormViewState(
  val textEntered: String,
  val isSubmitButtonEnabled: Boolean,
  val onTextEntered: (String) -> Unit, /* Callback when user modifies the text */
  val onSubmitButtonSelected: () -> Unit  /* Callback when user clicks submit button */)

Laimiux

class CommentFormView(val rootView: View) {
  // View binding logic
  val commentTextField: EditText = rootView.findViewById(R.id.comment_text_field)
  val submitButton: Button = rootView.findViewById(R.id.submit_button)
  
  // Our view update function, takes a view state
  // snapshot and updates the android views
  fun setViewState(state: CommentFormViewState) {
    commentTextField.text = state.textEntered
    submitButton.isEnabled = state.isSubmitButtonEnabled

Laimiux

data class CommentFormData(
  // defines what user has entered
  val comment: String,
  // defines if the entered comment is valid for submission
  val isCommentValid: Boolean,
  // defines if there is a submit request in progress
  val submitRequest: Lce<Comment>?
)

Laimiux

// User modifies the comment text field
data class TextChangedEvent(val enteredText: String)

// User clicks submit
data class SubmitCommentEvent(val comment: String)

Laimiux

class CommentFormViewModel {
  // Let's create a view state from the data provided.
  fun createViewState(
    data: CommentFormData,
    onTextChanged: (TextChangedEvent) -> Unit,
    onSubmitSelected: (SubmitCommentEvent) -> Unit
  ): CommentFormViewState{
    val isSubmitting = data.submitRequest?.let { it.isLoading} ?: false
    return CommentFormViewState(
      textEntered = data.comment,

Laimiux

class CommentViewModel(val model: CommentFormModel) {
   fun viewStateStream(): Flowable<CommentFormViewState> { 
     // define the relays that will allow to complete unidirectional data flow
     val textChangedEventRelay = PublishRelay.create<TextChangedEvent>()
     val submitEventRelay = PublishRelay.create<SubmitCommentEvent>()
     
     return model
       .dataStream(
         // We pass the user action flowables to the CommentFormModel 
         textChangedEvents = textChangedEventRelay.toFlowable(Backpressure.LATEST),

Laimiux

class CommentFormPresenter(val viewModel: CommentViewModel) {
  fun attach(view: CommentFormView) {
    // Don't forget to unsubscribe
    viewModel.viewStateStream().subscribe { state ->
      view.setViewState(state)
    }
  }
}